1. Field of the Invention
The present invention relates to a light source apparatus emitting a plurality of light beams, and an optical scanner for optically scanning a scanned surface by using the plurality of light beams emitted from the light source apparatus.
2. Description of the Related Art
In recent years, according to a development in digital technologies, various kinds of image forming apparatuses are used as image data output apparatuses. Among them, for example, a full-color laser printer is superior because of higher image quality and shorter output time.
A laser printer mainly comprises an optical system unit for image formation, that is, an optical scanner, by which a desired image corresponding to image data can be formed. More specifically, in the optical scanner, when a laser beam is emitted from a light source apparatus mainly in a state in which a polygon mirror is rotating at constant speed, the laser beam is reflected by the polygon mirror to be successively deflected, and the deflected laser beam repetitively scans a photosensitive drum. Then, an electrostatic latent image formed through scanning by the laser beam is developed by using a toner, and the developed image is transferred to a paper. Thereby, an image corresponding to the image data is formed on the paper. In a full-color laser printer, in order to reproduce a full-color image, for example, a light source apparatus including four light sources corresponding to four color, that is, yellow (Y), magenta (M), cyan (C), black (B) is mounted in the optical scanner, and four photosensitive drums corresponding to these four light sources is used to form an electrostatic latent image.
In order to achieve higher image quality in the full-color laser printer, for example, it is required to reduce an influence of a color shift in an image as much as possible. The “color shift” is a problem in image formation, that is, a shift between each color (Y, M, C and B) in an image finally formed mainly due to a shift in an optical path of the laser beam from the light source apparatus to the photosensitive drum. When the color shift occurs, color reproducibility of the image or the like declines, thereby resulting in a decline in image quality.
However, in a conventional full-color laser printer, there is a possibility that the optical path of the laser beam is largely shifted mainly due to design factors and operating environments, so measures to reduce the influence of the color shift have not been sufficient yet. In consideration of a recent rapid advance in digital technologies, higher image quality of the full-color laser printer is an urgent necessity.
Moreover, in the conventional full-color laser printer, in order to be capable of deflecting a plurality of laser beams, the polygon mirror is upsized. Thereby, power consumption required to actuate the polygon mirror becomes higher, and a rotating mechanism may become unstable due to vibrations or the like.